diff --git a/STPSLDemo/STPSLDemo.csproj b/STPSLDemo/STPSLDemo.csproj
index db7e8cf..94db809 100644
--- a/STPSLDemo/STPSLDemo.csproj
+++ b/STPSLDemo/STPSLDemo.csproj
@@ -44,7 +44,7 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
     <OutputPath>Bin\Release</OutputPath>
-    <DefineConstants>TRACE;SILVERLIGHT</DefineConstants>
+    <DefineConstants>TRACE;SILVERLIGHT=1</DefineConstants>
     <NoStdLib>true</NoStdLib>
     <NoConfig>true</NoConfig>
     <ErrorReport>prompt</ErrorReport>
diff --git a/SmartThreadPool/CallerThreadContext.cs b/SmartThreadPool/CallerThreadContext.cs
index e111a65..92ea771 100644
--- a/SmartThreadPool/CallerThreadContext.cs
+++ b/SmartThreadPool/CallerThreadContext.cs
@@ -1,5 +1,5 @@
 
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
 
 using System;
 using System.Diagnostics;
diff --git a/SmartThreadPool/EventWaitHandle.cs b/SmartThreadPool/EventWaitHandle.cs
index 178501d..25be07a 100644
--- a/SmartThreadPool/EventWaitHandle.cs
+++ b/SmartThreadPool/EventWaitHandle.cs
@@ -1,4 +1,4 @@
-#if (WindowsCE)
+#if (_WINDOWS_CE)
 
 using System;
 using System.Runtime.InteropServices;
diff --git a/SmartThreadPool/EventWaitHandleFactory.cs b/SmartThreadPool/EventWaitHandleFactory.cs
index 42d214e..3c9c849 100644
--- a/SmartThreadPool/EventWaitHandleFactory.cs
+++ b/SmartThreadPool/EventWaitHandleFactory.cs
@@ -1,6 +1,6 @@
 using System.Threading;
 
-#if (WindowsCE)
+#if (_WINDOWS_CE)
 using System;
 using System.Runtime.InteropServices;
 #endif
@@ -25,7 +25,7 @@ namespace Amib.Threading.Internal
         {
             AutoResetEvent waitHandle = new AutoResetEvent(false);
 
-#if (WindowsCE)
+#if (_WINDOWS_CE)
             ReplaceEventHandle(waitHandle, false, false);
 #endif
 
@@ -40,14 +40,14 @@ namespace Amib.Threading.Internal
         {
             ManualResetEvent waitHandle = new ManualResetEvent(initialState);
 
-#if (WindowsCE)
+#if (_WINDOWS_CE)
             ReplaceEventHandle(waitHandle, true, initialState);
 #endif
 
             return waitHandle;
         }
 
-#if (WindowsCE)
+#if (_WINDOWS_CE)
 
         /// <summary>
         /// Replace the event handle
diff --git a/SmartThreadPool/Exceptions.cs b/SmartThreadPool/Exceptions.cs
index 45a481f..1125b54 100644
--- a/SmartThreadPool/Exceptions.cs
+++ b/SmartThreadPool/Exceptions.cs
@@ -1,5 +1,5 @@
 using System;
-#if !(WindowsCE)
+#if !(_WINDOWS_CE)
 using System.Runtime.Serialization;
 #endif
 
@@ -68,7 +68,7 @@ namespace Amib.Threading
     }
 
 
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
     /// <summary>
     /// Represents an exception in case IWorkItemResult.GetResult has been canceled
     /// </summary>
diff --git a/SmartThreadPool/SLExt.cs b/SmartThreadPool/SLExt.cs
index 038daf3..0b894c8 100644
--- a/SmartThreadPool/SLExt.cs
+++ b/SmartThreadPool/SLExt.cs
@@ -1,4 +1,4 @@
-#if SILVERLIGHT
+#if _SILVERLIGHT
 
 using System.Threading;
 
diff --git a/SmartThreadPool/STPEventWaitHandle.cs b/SmartThreadPool/STPEventWaitHandle.cs
index 02f7e0e..33936d2 100644
--- a/SmartThreadPool/STPEventWaitHandle.cs
+++ b/SmartThreadPool/STPEventWaitHandle.cs
@@ -1,4 +1,4 @@
-#if !(WindowsCE)
+#if !(_WINDOWS_CE)
 
 using System;
 using System.Threading;
diff --git a/SmartThreadPool/STPPerformanceCounter.cs b/SmartThreadPool/STPPerformanceCounter.cs
index 263c586..52ab742 100644
--- a/SmartThreadPool/STPPerformanceCounter.cs
+++ b/SmartThreadPool/STPPerformanceCounter.cs
@@ -23,7 +23,7 @@ namespace Amib.Threading.Internal
         void SampleWorkItemsWaitTime(TimeSpan workItemWaitTime);
         void SampleWorkItemsProcessTime(TimeSpan workItemProcessTime);
     }
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
 
     internal enum STPPerformanceCounterType
 	{
diff --git a/SmartThreadPool/SmartThreadPool.cs b/SmartThreadPool/SmartThreadPool.cs
index fbae208..58f5e2a 100644
--- a/SmartThreadPool/SmartThreadPool.cs
+++ b/SmartThreadPool/SmartThreadPool.cs
@@ -265,7 +265,7 @@ namespace Amib.Threading
         private ISTPInstancePerformanceCounters _localPCs = NullSTPInstancePerformanceCounters.Instance;
 
 
-#if (WindowsCE)
+#if (_WINDOWS_CE)
         private static LocalDataStoreSlot _threadEntrySlot = Thread.AllocateDataSlot();
 #else
         [ThreadStatic]
@@ -295,7 +295,7 @@ namespace Amib.Threading
         /// </summary>
         internal static ThreadEntry CurrentThreadEntry
         {
-#if (WindowsCE)
+#if (_WINDOWS_CE)
             get
             {
                 return Thread.GetData(_threadEntrySlot) as ThreadEntry;
@@ -398,10 +398,10 @@ namespace Amib.Threading
 
             _isSuspended = _stpStartInfo.StartSuspended;
 
-#if (WindowsCE) || (SILVERLIGHT)
+#if (_WINDOWS_CE) || (_SILVERLIGHT) || (_MONO)
 			if (null != _stpStartInfo.PerformanceCounterInstanceName)
 			{
-                throw new NotSupportedException("Performance counters are not implemented for Compact Framework/Silverlight");
+                throw new NotSupportedException("Performance counters are not implemented for Compact Framework/Silverlight/Mono, instead use StpStartInfo.EnableLocalPerformanceCounters");
             }
 #else
             if (null != _stpStartInfo.PerformanceCounterInstanceName)
@@ -609,7 +609,7 @@ namespace Amib.Threading
 					// Configure the new thread and start it
 					workerThread.Name = "STP " + Name + " Thread #" + _threadCounter;
 					workerThread.IsBackground = true;
-#if !(SILVERLIGHT)
+#if !(_SILVERLIGHT)
 					workerThread.Priority = _stpStartInfo.ThreadPriority;
 #endif
 					workerThread.Start();
@@ -779,7 +779,7 @@ namespace Amib.Threading
 			{
                 tae.GetHashCode();
                 // Handle the abort exception gracfully.
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
 				Thread.ResetAbort();
 #endif
 			}
@@ -939,7 +939,7 @@ namespace Amib.Threading
 				{
                     
 					if ((thread != null)
-#if !(WindowsCE)
+#if !(_WINDOWS_CE)
                         && thread.IsAlive
 #endif                        
                         )
diff --git a/SmartThreadPool/SmartThreadPoolCE.csproj b/SmartThreadPool/SmartThreadPoolCE.csproj
index 4ca0771..10203f3 100644
--- a/SmartThreadPool/SmartThreadPoolCE.csproj
+++ b/SmartThreadPool/SmartThreadPoolCE.csproj
@@ -32,7 +32,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>TRACE;DEBUG;WindowsCE,_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;_WINDOWS_CE,_WINDOWS</DefineConstants>
     <NoStdLib>true</NoStdLib>
     <NoConfig>true</NoConfig>
     <ErrorReport>prompt</ErrorReport>
@@ -44,7 +44,7 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
     <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE;WindowsCE,_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE;_WINDOWS_CE,_WINDOWS</DefineConstants>
     <NoStdLib>true</NoStdLib>
     <NoConfig>true</NoConfig>
     <ErrorReport>prompt</ErrorReport>
diff --git a/SmartThreadPool/SmartThreadPoolMono.csproj b/SmartThreadPool/SmartThreadPoolMono.csproj
index c5f7e37..ce4c31f 100644
--- a/SmartThreadPool/SmartThreadPoolMono.csproj
+++ b/SmartThreadPool/SmartThreadPoolMono.csproj
@@ -18,7 +18,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>.\bin\Debug\</OutputPath>
-    <DefineConstants>TRACE;DEBUG;NO_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;_MONO</DefineConstants>
     <DocumentationFile>
     </DocumentationFile>
   </PropertyGroup>
@@ -26,7 +26,7 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
     <OutputPath>.\bin\Release\</OutputPath>
-    <DefineConstants>TRACE;NO_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE;_MONO</DefineConstants>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
diff --git a/SmartThreadPool/SmartThreadPoolSL.csproj b/SmartThreadPool/SmartThreadPoolSL.csproj
index abbf75c..76f1fcb 100644
--- a/SmartThreadPool/SmartThreadPoolSL.csproj
+++ b/SmartThreadPool/SmartThreadPoolSL.csproj
@@ -25,7 +25,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>Bin\Debug</OutputPath>
-    <DefineConstants>TRACE;DEBUG;SILVERLIGHT,_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE;DEBUG;_SILVERLIGHT,_WINDOWS</DefineConstants>
     <NoStdLib>true</NoStdLib>
     <NoConfig>true</NoConfig>
     <ErrorReport>prompt</ErrorReport>
@@ -35,7 +35,7 @@
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
     <OutputPath>Bin\Release</OutputPath>
-    <DefineConstants>TRACE;SILVERLIGHT,_WINDOWS</DefineConstants>
+    <DefineConstants>TRACE;_SILVERLIGHT,_WINDOWS</DefineConstants>
     <NoStdLib>true</NoStdLib>
     <NoConfig>true</NoConfig>
     <ErrorReport>prompt</ErrorReport>
diff --git a/SmartThreadPool/WorkItem.cs b/SmartThreadPool/WorkItem.cs
index 5d0e221..1641691 100644
--- a/SmartThreadPool/WorkItem.cs
+++ b/SmartThreadPool/WorkItem.cs
@@ -61,7 +61,7 @@ namespace Amib.Threading.Internal
 		/// </summary>
 		private object _state;
 
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
         /// <summary>
         /// Stores the caller's context
         /// </summary>
@@ -209,7 +209,7 @@ namespace Amib.Threading.Internal
 			_workItemsGroup = workItemsGroup;
 			_workItemInfo = workItemInfo;
 
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
 			if (_workItemInfo.UseCallerCallContext || _workItemInfo.UseCallerHttpContext)
 			{
 				_callerContext = CallerThreadContext.Capture(_workItemInfo.UseCallerCallContext, _workItemInfo.UseCallerHttpContext);
@@ -360,7 +360,7 @@ namespace Amib.Threading.Internal
         private void ExecuteWorkItem()
         {
 
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
             CallerThreadContext ctc = null;
             if (null != _callerContext)
             {
@@ -405,13 +405,13 @@ namespace Amib.Threading.Internal
                 // work items was cancelled.
                 if (!SmartThreadPool.CurrentThreadEntry.AssociatedSmartThreadPool.IsShuttingdown)
                 {
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
                     Thread.ResetAbort();
 #endif
                 }
             }
 
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
             if (null != _callerContext)
             {
                 CallerThreadContext.Apply(ctc);
@@ -708,7 +708,7 @@ namespace Amib.Threading.Internal
 		/// <returns>Returns true on success or false if the work item is in progress or already completed</returns>
         private bool Cancel(bool abortExecution)
 		{
-#if (WindowsCE)
+#if (_WINDOWS_CE)
             if(abortExecution)
             {
                 throw new ArgumentOutOfRangeException("abortExecution", "WindowsCE doesn't support this feature");
diff --git a/SmartThreadPool/WorkItemsGroup.cs b/SmartThreadPool/WorkItemsGroup.cs
index d5bec6b..d8b133b 100644
--- a/SmartThreadPool/WorkItemsGroup.cs
+++ b/SmartThreadPool/WorkItemsGroup.cs
@@ -88,7 +88,7 @@ namespace Amib.Threading.Internal
 			{
 				throw new ArgumentOutOfRangeException(
                     "concurrency", 
-#if !(WindowsCE) && !(SILVERLIGHT)
+#if !(_WINDOWS_CE) && !(_SILVERLIGHT)
                     concurrency,
 #endif
                     "concurrency must be greater than zero");
diff --git a/SmartThreadPool/WorkItemsQueue.cs b/SmartThreadPool/WorkItemsQueue.cs
index d948ddb..e7e265a 100644
--- a/SmartThreadPool/WorkItemsQueue.cs
+++ b/SmartThreadPool/WorkItemsQueue.cs
@@ -33,7 +33,7 @@ namespace Amib.Threading.Internal
         private bool _isWorkItemsQueueActive = true;
 
 
-#if (WindowsCE)
+#if (_WINDOWS_CE)
         private static LocalDataStoreSlot _waiterEntrySlot = Thread.AllocateDataSlot();
 #else
 
@@ -47,7 +47,7 @@ namespace Amib.Threading.Internal
         /// </summary>
         private static WaiterEntry CurrentWaiterEntry
         {
-#if (WindowsCE)
+#if (_WINDOWS_CE)
             get
             {
                 return Thread.GetData(_waiterEntrySlot) as WaiterEntry;